Recirculating process and apparatus for gas purification



Nov. 6, 1928. v 1,690,438

F. w. SPERR, JR

RECIRCULATING PROCESS AND APPARATUS FOR GAS PURIFICATION Original Filed June 6, 1924 2 Sheets-Sheet 1 gwv entoz 5% M (1 f k Nov. 6, 1928. 1,690,438

F. w. sPERR, JR

RECIRCULATING PROCESS AND APPARATUS FOR GAS PURIFICATION Original Filed June 6. 1924 2 Sheets-Sheet 2 com rising1 Patented Nov. 6, 1928.

1,690,438 PATENT OFFICE.

FREDERICK W. SPEED, 33., OF PITTSBURGH, PENNSYLVANIA, ASSIGNOB TO THE KOPPEBS COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION 01: PENN- SYLVANIA.

BECIBOULATING PROCESS AND APPARATUS FOR GAS PIIBIFICATION.

Application filed June 6, 1924, Serial No. 718,255. Renewed January 28, 1928;

This invention relates to processes and aparatus for the purification of gases, of the hind involving the. steps of transferringthe impurities to a stream of air and purifying the air with a washing liquid whic 1 may incidentall be regenerated by the air with separation o the impurities in easily recoverable form. 1

The invention is more particularly applicable to the elimination of hydrogen sulphide from coal as and like fuel gases as described in m app ication filed of even date herewith, Ser. os. 718,253, filed June 6, 1924 and 718,- 254, filed June 6, 1924 and the-application of Gilbert Edward Seil Ser. No. 718,204, filed June 6, 1924' also filed of even date herewith. The invention consists broadly in recircu-' lating the air from which the impuritieshave been removed back to the gas purification stage. By this operation the discharge into the atmosphere of any material that might cause odor is substantially avoided, because the air employed in the process circulates in v a closed path with the exception of losses due as to leakage and the absor tionsof oxygen in the chemical reactions 0 the process, which losses are compensated by adding fresh air to the system to the extent found necessary.

The invention also consists in providing apparatus for carrying out the new process, means for transferring impurities rom t e gas to a stream of, air, in combination with a scrubber for purifying the air, connections which unite in a closed circuit 5 the air scrubber and the chamber in which the air takes up the impurities extracted from the gas, and a device for circulating the air through said circuit. I

The invention further consists in such other I new and useful improvements, and has for further objects such other operative advantages or results, as may be found to obtain in theprocesses and apparatus hereinafter described or claimed. r

U c In order that the invention may be understood, there will now be described by way of example and with reference to the accompanylng drawings, a preferred mode of car rying out the process and two arrangements of apparatus with which the process may be earned out, as applied to the elimination of hydro en sulphide from coal gas j In t ese drawings: Figure 1 is a general elevational view of a complete plant for the elimination of hydrogen sulphide from coal gas, with circula-- of the gas with freshly regenerated air washing liquid to remove the last traces of hydrogen'sulphide, and arrangement of all the devices in a sin le tower.

The first was ling, by which about 90% of the H S is removed, is effected in the primar absorber or scrubber 1 at the top of the le t hand section of the single tower, with a solution of sodium carbonate. The gas enters the absorber 1 by the inlet 2, flows upwards in counter-current with the solution delivered through a pipe 3, and then passes through an opening 4 in artition 33 which divides the tower longitu inally, into the top of the secondary absorber 30 located at the upper right hand side of the partition 33. In the secondary absorber the gas. is washed with a freshly regenerated alkaline solution containing suitable iron compound, preferabl freshly precipitated in accordance with t e invention in my application Ser. No. 718,253 aforesaid, the primary function of which liquid is to "purify the air as described hereinafter. The liquid has a great avidity for hydrogen sulphide and is extremely effective in absorb-' ing the last traces of the same from the gas in the secondary absorber 30. The gas flows downwards through the absorber 30 and is discharged through the outlet 31.

The sodium carbonate solution flows: from the bottom of the primary absorber 1 through pipes 5 into the top of the actifier 7 which is located immediately underneath the absorber 1. The solution falls through the actifier to the bottom thereof and fiows off through a pipe 8 into a sump 9 from which it is withdrawn by a pump 10 and pipe 11 and thence recirculated to the top of the absorber 1; The

solution flows in countercurrent in the actifier 7 with a stream of air sup lied by a blower 12 whereby the alkaline so ution 1S regenerated and the hydrogen sulphide transferred scrubber. In the air scrubber the air is washed with the liquid containing the ,iron' compound which has alread functioned in the secondary absorber 30 an which, because of the comparativel small amount of H,S

which it has absorbe' therein, has suffered no appreciable deterioration of its' air purifying qualities. This washing liquid as well as the air, is introduced at the to of the scrubber 14, and through pipes 15 an sprayers 16, and

after traversing the scrubber downwardly,

that is, in the same direction as the air, the liquid flows off through a pipe 18 into a sump 19. The liquid is regenerated concurrently with the purification of the air while traversing the scrubber .14 and the regeneration is completed in the sump b means of air jets 20 which also agitate the liquid and mechanically float the sulphur to the surface thereof from which it is readily removed by skimming and dried in the centrifuge 28. The air washing liquid is umped from the sump 19 by the pump 24 an through pipes 23, 32, and

sprayers, to the top of the secondary absorber wherein it functions in the manner previously described.

According to the resent invention the air which has been puri ed in the air scrubber 14 is not discharged into the atmosphere but is led back to the actifier chamber and utilized therein for aerating further quantities of sodium carbonate solution. The air thus circulates in a closed ath and traverses alternately the air scrub er 14 and the actifier 7 so that there is substantial avoidance of discharging into the atmos here anything that might cause odor. Fres air is added to the circulation as found necessary to replace losses of air by leakage and absorption of oxygen in the chemical reactions involved in the process.

In the plant shown in Fig. 1, the air is circulated by a blower 12 having its connections and 51 to the lower ends of the air scrubber 14 and actifier 7 respectively. The air circulates through the closed circuit comprising the blower 12, actifier 7, scrubber 14 and connections 50, 51 in the direction shown by the arrows, the pressure connection from the blower leading to the actifier.

In the plant shown in Fig. 2, which is the preferred arrangement, a b ower is used and the connections 50, 51 are joined to the upper ends of the actifier 7 and air scrubber 14 respectively. The air traverses the partition 33 near the bottom through the o ening 13 provided with solution baffles, an circulates can be replaced, if desired, by the porous plate device described in said last mentioned application. Y

The invention as hereinabove set forth or exemplified may be variously racticed or embodied within the scope o the claims hereinafter made.

1. A process of the kind referred to for the purification of ases involvin the steps of washing gas wit a li uor to a sorb impurities, aeratin such wa liquor to regenerate the same an washing the air to remove the the air from which the impurities have been rtemoved back to the liquid regeneration s age.

2. process for the purification of gases comprising the stepsof washing the gas with an mpurity absorbm liquid, aerating the llqllld to regenerate t e same and transfer the impurities to a stream of air, washing the I in the path indicated by arrows, the suction impurities, characterized by recirculating air with an impurity absorbing liquid with concurrent regeneration of the liquid, and circulating the air in a closed path alternately through the aeration. and the air washing stages.

3. A process as claimed in claim 2, in which the gas is subjected to a second washin effected with freshly regenerated air was ing liquid prior to the entry of said liquid into the air purification stage.

4 A process as claimed in claim 2, in which the circulation of the air through the actifir is effected by suction.

5. process as claimed in claim 2, in which the circulation of the air through the actifier is effected by pressure.

6. process as claimed in claim 1, in which the air purification stage is efiected with unidirectional movement of the air and the washing liquid for same.

7. A process as claimed in claim 1, ap lied to the elimination of hydrogen sulphide om coal gas and like fuel gases.

8. A process as claimed in claim 1, applied I 9. Apparatus for out the process of claim 1 comprising means for transferring impurities from the gas to a stream of air, in combination with a scrubber for purifying the air, connections which unite in a closed circuit the air scrubber and the chamher in which the air takes up the impurities extracted from the gas, and a device for circulatingc the air through said circuit.

10. Apparatus as claimed in claim 9 comprising two towers in one of which are located in superposition a primary absorber and an actifier for the gaswashing liquid used in said absorber, and in the other of which are similarly located a secondary absorber and the air scrubber, the primary and secondary absorbers being so connected that the gas to be purified traverses them in series, and the actifier and air scrubber being so connected that the air circulates in a closed path through them in alternation.

actifier for the gas washing liquid used in said absorber, while in the other chamber are located the secondary absorber and the air scrubber, the primary and secondary absorbers being so connected that the gas to be purified traverses them in series, and the actifier and air scrubber being so connected that the air. circulates in a closed path through them in alternation.

In testimony whereof I have hereunto set my hand.

FREDERICK W. SPERR, JR. 

